Control for reducing air loads on wings



Feb. 14, 1956 R. voc-:.1 l 2,734,704

CONTROL FOR REDUCING AIR LOADS ON WINGS Filed April 1. 1952 5Sheets-Sheet 1 F1a J.

BY ma 65M- nab., ma

HTI'QE/VEY Feb. 14, 1956 R. voG'r CONTROL FOR REDUCING AIR LOADS ONWINGS Filed April 1, 1952 3 Sheets-Sheet 2 INVENTOR 13m/MED V047' Feb.14, 1956 R, VOG-r 2,734,704

CONTROL FOR REDUCING AIR LOADS ON WINGS Filed April l, 1952 3Sheets-Sheet 3 INVEN TOR. ,efe/Me V047 United States Patent O 2,734,704CONTROL FOR REDUCIN G AIR LOADS ON WINGS Richard Vogt, Medway, OhioApplication April 1, 1952, Serial No. 279,905

2 Claims. (Cl. 244-82) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described in the following specification and claimsmay be manufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereon.

This invention relates to a method for reducing the weight of airplanewings by reducing the bending moments on the wings and to offset gustloads on the wings. This is accomplished by automatically making theailerons respond negatively to an increase in the angle of attack whichcauses the increase in bending moments on the wings.

The basic idea of this invention consists in detecting the increase ofairloading on the wing and to translate this increase into a movement ofthe ailerons to oiset the increase of the airloading on the outerportion of the wing. In this way the center of the lift will shiftinwardly, thereby decidedly reducing the bending moments.

A sudden gust of air or an extended maneuver results in an increase ofair loading on an aircraft wing. The increase in bending momentstherefore increases the load factor necessary in designing the wing. Thewing spar makes up the greater structural weight of the wing so that adecrease in the bending moments on the wing can result in a decrease inthe weight of the wing spar. It is therefore an object of this inventionto decrease the bending moments on the aircraft wing and therebyclecrease the weight of the airplane wings.

When an upward gust of wind hits the wings, the increase in the bendingmoment will tend to make the wings bend. An electrical or mechanicaldetecting device for converting this deflection to an auxiliary aileroncontrol and then to the aileron is provided so that the aileron willmove in a direction to reduce the air loads on the wings.l Anotherobject of this invention therefore is to provide a method of detectingthe accelerations due to air load changes on the wings.

These and other objects will become apparent from the accompanyingspecification and drawings wherein like parts refer to like numbers andwherein:

Fig. 1 is a broken plan view showing an airfoil and auxiliary aileroncontrol.

Fig. 2 is a cross View taken on line 2 2 of Fig. 1 showing theconnection to the aileron.

Fig. 3 is a front view taken along line 3--3 of Fig. 1 showing thedetecting device.

` Fi'g. -4 is a front view of an airplane showing another embodiment ofthe invention. Y

Fig. `5 shows the piston and cylinder arrangement of Fig. 4 with theaileron and auxiliary controls.

Fig. 6 is a cross section view of the wing of Fig. 4 showing the deviceconnected to the aileron.

Figs. 7 and 8 show a wing having an electrical means of detecting andtransmitting the effect of gust loads.

Referring to Figs. l3, 10 is an aircraft wing with an aileron 11pivotally mounted thereon, said wing having mounted thereon an air-loaddetecting device generally ICC designated as 12 and an kauxiliaryaileron control generally designated as 14 connected to the detectingdevice 12. The airload detecting device 12 comprises an auxiliaryairfoil section 16 on an arm 18 extending outwardly in a spanwisedirection of the aircraft wing 10. The airfoil can extend in front ofthe wing instead of spanwise. Said arm 18 is xedly mounted to a rod 20pivotally mounted in the aircraft wing 10. The auxiliary aileron control14 comprises an arm 22 fixed to said rod 20, and having a link 24pivotally connected to said arm 22. The other end of said link 24 ispivotally connected to a piston rod 26. Said piston rod 26 having apiston 27 fixed thereon extends through both ends of cylinder 28 to keepthe piston rod and cylinder in yalignment and is normally held in anextended position by coil springs 30 biased against pistons 29, slidablymounted on piston yrod 26 and cylinder heads 31 in said cylinder 28.Said cylinder 28 is rigidly secured to the aircraft structure at 33. Abracket 32 extending from said piston rod 26 pivotally carries a bellcrank 34. A link 36 is pivotally connected to said bell crank at oneend, and is pivotally connected to a bracket 38 on the aileron 11 at theother end. The normal aileron control system comprises a control rod 40pivotally connected at the other end of the bell crank 34 for normallyoperating the aileron.

In operation a gust of wind on the airfoil 16 will force the airfoil inan upward direction, which will pivot the arm 22 in a counterclockwisedirection, and which will in turn force the link 24 and piston 26inwardly so that piston 27 will engage piston 29 compressing the spring30. Since the pilot will normally be holding the stick steady for thevnormal aileron control, the bell crank 34 will assume a new positionwhich will tend to exert a pull on the link 36 and pivot the aileron inan upward direction. This upward movement of the aileron 12 will reducethe. lift and partly or fully offset the force due to the gust of windon the wing 10. The coil springs 30 will tend to maintain the airfoil 16in a neutral position until the airload on the airfoil exceeds apredetermined value. Also, the normal aileron control may be operatedindependently of the auxiliary aileron control since the springs aresuiciently stili as not to give while the normal aileron control is inuse.

Referring to the modification shown in Figs. 4-6 the wings 5t) and 52are mounted in the fuselage 54 at 56 and 58. A central member 6) ismounted in the fuselage 54 to which is connected a cable 70 at each sideat 62 and 64. The cable 70 is wound around pulleys 66 and 68, thepulleys being pivotally mounted at S6 and 5S. Said cable 70 is connectedto an arm 61 which is pivotally mounted in the wing 50 at 63. A cable 71is connected to the arm 61 and piston rod 72. The arm arrangementampliies the shortening of the cable 70 sopas to give greater movementto the piston rod 72. Said piston rod 72, having an integral piston 73,is mounted in a cylinder 74 securely mounted to the aircraft structurein the airplane at 75. Springs 76 tend to hold piston 73 and the pistons77 inthe cylinder 74 in a neutral position since they are slidablymounted on the piston rod 72. Figure 5 shows the piston 73 in apartially operative position. A bracket 78 mounted on said cylinder 74carries a bell crank 80 which has a link 82 pivotally connected thereto.A bracket 84 lixedly mounted onisaid aileron 11 is pivotally connectedto said link 82. Y The normal aileron control comprises a link 86pivotally connected to said piston rod 72, and one end of link 88pivotally connected to said link 86. `The other end of said link 88 isin turn pivotally connected to one end of the bell crank 80. The link 86is pivotally connected to control rod which is in turn pivotallyconnected to the pulley 87. The pulley 87 is operated by the normalaileron control cable 89.

In this modification the whole aircraft wing becomes a detecting deviceso that an increase in air loading, for example, in an upward directionwill tend to pivot the wing about 56. In View of this angular deflectionof the wing, cable will shorten because of moving around pulley 66,thereby pulling on the arm 61 and cable 71 against the spring 76. Sincethe pilot will be holding the stick steady, the piston 72 and link 86will assume the positions shown in Fig. 5. In,this position the arm 88will tend to pivot the bell crank 80 in a counterclockwise direction,which will force the link 82' to turn bracket 84 in a counterclockwisedirection. This will force the aileron 11 in an upward direction anddecrease the lift to counterbalance the additional air load on thewings.

In the modifications described coil springs 30 and 76 are sufficientlystrong enough so as not to be affected by the operation of the normalaileron control. In this way the movement of the stick will operate theaileron control independent of the auxiliary aileron control.

Referring to Figures 7 and 8, an electrical system is shown incombination with the airfoil. The airfoil 16 extends forward on the wing10 and has an arm 18 connected thereto. The arm 18 is rigidly connectedto a rod which is pivotally mounted in brackets 92 which are connectedto the structure of the wing. The rod 90 is also operably connected toselsyn pickos 94 and 95 which are in turn connected to a phase sensitiveamplifier 96 which is in turn electrically connected to a two phasemotor 98 which drives a worm 100. Reduction gears 101 and 103 areconnected to worm 100. A shaft or coupling 105 connects the reductiongears to the selsyn 95. The worm 100 has a guide 102 threadedly mountedthereon. The said guide is mounted on guide shafts 104 which are in turnmounted in brackets 106 which are connected to the structure of theaircraft. The bell crank 34 is pivotally mounted on the guide 102. A rod82 is pivotally connected to one end of the bell crank 34 and to theaileron 11. The other end of the bell crank 34 has a control rod 40connected thereto. The

arm 18 has spring seats 110 mounted thereon. Springseats 112 are alsomounted in the wing in alignment with spring seats for carrying springs108. springs 10S keep the airfoil 16 in a neutral position until asutiicient predetermined airload is exerted on the airfoil, so that thenormal aileron control may operate independently.

Upon movement of the airfoil 16, a signal will be transmitted to theselsyn pickoifs which will in turn be delivered to the phase sensitiveamplifier which will energize the motor and turn the worm 100, whereuponthe guide 102 will move in accordance therewith and transmit this motionto the bell crank 34 and rod 82,

so that the aileron will be actuated. The selsyn pickofs will tend toreturn the guide 102 to a neutral position after the gust load has beenremoved.

It is apparent that the specific embodiments shown above have been givenby way of illustration and not by way of limitation and that thestructures above described are subject to wide variation andmodification without departing from the scope or intent of theinvention, all of which variations and modications are to be consideredas equivalents and be included within the scope 5;.

of the present invention.

i claim: n

l. Gust alleviating means for aircraft wings, comprising in combinationwith an aircraft wing, an aileron pivotally mounted on said wing, aprimary control sys- The ii tem for actuating said aileron to vary thelift over the wing, asecondary control system for said aileron operableto actuate said aileron independent of actuation thereof by said primaryaileron control system, gust detecting means comprising an auxiliaryairfoil pivotally supported on said wing to be responsive to gust airloads acting on said wing, said primary control system comprising a bellcrank pivotally and bodily shiftable in the wing, a control rod pivotedto one arm of said bell crank and adapted to pivot the bell crank aboutits center, and a link pivoted' to the other arm of said bell crank,said link being pivotally connected to anl operating arm bracket mountedon the aileron, said auxiliary airfoil extending outward in a spanwisedirection from said wind and' operatively connected to said bell crankcenter for bodily displacement of the bell crank pivot upon movement ofsaid auxiliary airfoil, when said control rod is held stationary torotate said bell crank about one arm pivot connection thereof to shiftsaid link and said bracket to pivot said aileron, yielding means biasingsaid auxiliary airfoil to a neutral position until the air load thereonexceeds a predetermined value.

2. Gust alleviating means for aircraft wings, comprising in combinationwith an aircraft wing, an aileron pivotally mounted on saidI wing, aprimary control systern for actuating said aileron to varyV the liftover the wing, a secondary control system for said aileron operablev tolactuate said aileron independently of actuation thereof by said primaryaileron control system, said primary control system comprising a bellcrank, a control rod pivotally connected to one end of saidv bellcrank,V

and a link pivotally connected to the other end of said bell crank, saidlink being pivotally connected to a bracket mounted on said aileron,said secondary control system comprising anjauxiliary air foilresponsive to gust air loads extending outwardly in a spanwise directionfrom said wing, said auxiliary air f'oil being pivotally mounted in thewing and operatively connected to a piston rod, a piston fixed on saidrod, a cylinder fixed in said wing surrounding said rod and piston,cylinder heads at the ends of said cylinder, said piston rod slidablyextending through both ends of the cylinder heads with the piston fixedthereon between the cylinder heads, a pair of pistons slidably mountedon said rod, one on each side of the lirst mentioned piston for abutmentwith said fixed piston, an abutment in the cylinder intermediate theslidable pistons for limiting movement of each of the slidablev pistonsin an inward direction, a coil spring mounted between each of thecylinder heads and said sliding pistons for yieldingly holding saidpistonv rod against longitudinal movement, one of said springs beingcompressedv upon movement of said rod` by said auxiliary air foil in.one direction and the other by movement of the air foil in the oppositedirection, said bell crank being pivotally mounted on said piston rodand operating by movement of said piston rod, said bell crank operatingsaid link and bracket to pivot said aileron upon movement of said pistonrod when said control rod is held stationary, said coil springs biasingsaid auxiliary air foil to a neutral position until air load thereonexceeds a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS

